3GPP (3rd Generation Partnership Project) defines techniques related to various mobile communication systems and, for example, defines a technique related to LTE (Long Term Evolution) as a wireless access method in a mobile communication system. In the LTE, available radio resources are allocated to a communication terminal (which is referred to hereinafter as a UE (User Equipment)). A UE can receive downlink data or transmit uplink data by using the allocated radio resources.
A UE receives downlink data using the radio resources allocated to the UE through the PDSCH (Physical Downlink Shared Channel) defined in the 3GPP. Further, a UE can recognize the radio resources allocated to the UE by receiving the PDCCH (Physical Downlink Control Channel) defined in the 3GPP. The radio resources allocated to a UE are subframes, for example. A UE can receive downlink data by decoding downlink data transmitted in a scheduled subframe, for example. Subframe scheduling information is set to the PDCCH.
The subframe scheduling method includes dynamic scheduling and multi-subframe scheduling. In dynamic scheduling, a subframe for transmitting downlink data and a subframe for transmitting control information (PDCCH) containing scheduling information for using the subframe or the like are the same. Thus, for each subframe, the scheduling information of the subframe is set.
On the other hand, in multi-subframe scheduling, scheduling information of a plurality of subframes allocated to a UE are set in one control information. Thus, a subframe allocated to a UE may be different from a subframe in which control information is transmitted. By using multi-subframe scheduling, it is possible to reduce the PDCCH for transmitting the scheduling information of downlink data and reduce the overhead of a control signal.
Patent Literature 1 discloses a technique that defines a new DCI (Downlink Control Information) format in multi-subframe scheduling, and sets scheduling information regarding Multi-subframe scheduling by using the new DCI format.